Long-term outcomes of shelf acetabuloplasty for developmental dysplasia of the hip in adults: a minimum 20-year follow-up study

BACKGROUND Shelf acetabuloplasty has been applied to secondary osteoarthritis of the hip due to congenital dislocation or acetabular dysplasia; however, there are few reports on the long-term outcomes of this operation. Here, we aimed to investigate the long-term effects of our shelf acetabuloplasty for developmental dysplasia of the hip in adults. METHODS Outcomes for 28 hips (7 with pre-arthrosis, 21 with initial stage of arthrosis) were retrospectively reviewed clinically and radiologically at a minimum of 20 years after operation. Mean age of the patients at operation was 34 years (range 17-54 years), and the mean follow-up period was 25 years (range 20-32 years). RESULTS Mean Japanese Orthopaedic Association hip score improved from 76 points preoperatively to 82 points, and mean pain score improved from 24 points preoperatively to 33 points at 20 years. Mean Sharp angle improved from 51° preoperatively to 37° immediately after the operation. Similarly, the mean center-edge angle improved from -4° to 38°, and the mean acetabulum head index improved from 52 to 99%. More than 50% of the hips showed no change in joint space width at 20 years. Survival rates were 100% at 10 years, 93% at 20 years and 71% at 32 years, with conversion to total hip replacement as the endpoint. CONCLUSION Long-term outcomes of our shelf acetabuloplasty were comparable to other reports, and the clinical outcomes and survivorship revealed positive long-term effects of our procedure over approximately 20 years.